The technology for the production of radiation curable coatings using acrylate-functional oligomers is known. The article "Coatings", Encyclopedia of Polymer Science and Engineering, supp. vol., p. 109 and 110 (John Wiley & Sons, Inc. N.Y., N.Y., 1989) notes the most widely used vehicle systems are oligomers substituted with multiple acrylate ester groups mixed with low molecular weight monofunctional, difunctional, or trifunctional acrylate monomers.
U.S. Pat. No. 4,522,465 (Bishop, et. al.) discloses buffer-coated and overcoated optical glass fiber in which the topcoat has the high strength and high tensile modulus combined with good elongation and solvent resistance associated with extruded jacket coatings, but which is applied by ordinary coating procedures and cured by exposure to ultraviolet radiation. The coating compositions comprise 30% to about 80% of linear diethylenic polyester polyurethanes which are the linear polyurethane reaction product of an organic diisocyanate with hydroxy-functional polyester formed by reacting a diol, such as ethylene glycol, with certain dicarboxylic acids, such as adipic acid. This polyurethane is end capped with a monoethylenically unsaturated monohydric alcohol, e.g. the hydroxy-functional acrylate of caprolactone dimer derived from caprolactone and 2-hydroxyethyl acrylate supplied by Union Carbide Corporation under the designation Tone M-100.
U.S. Pat. No. 4,581,407 (Schmid) discloses an essentially isocyanate-free polyurethane polyurea polyethylenic oligomer which is unusually strong and elastic and is thus useful as a binder for a coating containing a magnetic pigment. This oligomer is the reaction product of: (1) organic diisocyanate; (2) a stoichiometric deficiency of difunctional materials reactive therewith and consisting essentially of: (A) polyoxyalkylene glycol having a molecular weight of from 200 to 1000; (B) dihydric bisphenol-based alkylene oxide adduct containing from 2-10 alkylene groups per molecule; and (C) polyoxyalkylene diprimary amine having a molecular weight of from 150 to 800. In all of these, the alkylene groups contain from 2-4 carbon atoms. The polyurethane polyurea so-constituted is capped with monohydric ethylenic compound, such as the adduct of caprolactone dimer and 2-hydroxyethyl acrylate, to provide a molecular weight in the range of about 5,000 to about 30,000. This polyethylenic oligomer is cured by radiation exposure, such as an electron beam, using from 5% to 25%, based on total polymer solids, of polyethylenic polyhydroxyalkyl melamine.